초록 ▼

The present invention relates to a measurement-while-drilling (MWD) tool having a pressure compensation system and reservoir segregated from fluid integration with actuator mechanism lubricants. The MWD tool can also be serviced on the rig floor without the need to drain, reseal and charge the compe

The present invention relates to a measurement-while-drilling (MWD) tool having a pressure compensation system and reservoir segregated from fluid integration with actuator mechanism lubricants. The MWD tool can also be serviced on the rig floor without the need to drain, reseal and charge the compensation system.

대표청구항 ▼

The invention claimed is: 1. An isolated pressure compensation system for a Measurement-While-Drilling Tool, comprising: a pressure balance chassis; a circumferential relief on the exterior surface of the pressure balance chassis; a pliable cylindrical bladder circumferentially surrounding the reli

The invention claimed is: 1. An isolated pressure compensation system for a Measurement-While-Drilling Tool, comprising: a pressure balance chassis; a circumferential relief on the exterior surface of the pressure balance chassis; a pliable cylindrical bladder circumferentially surrounding the relief, and forming a pressure compensating reservoir; a pair of clamps, circumferentially sealing the bladder to the pressure balance chassis above and below the pressure compensating reservoir; an interior bore extending through the center of the pressure balance chassis; a pressure balance rod slidably located in the interior bore; an enlarged cylinder portion formed on the interior bore; a fluid passage between the reservoir and the cylinder portion; a piston formed on the pressure balance rod, the piston being axially slidable within the cylinder portion of the pressure balance chassis, and being located interior of the pressure compensating reservoir; a piston seal located on the piston, providing a fluid seal between the piston and the cylinder bore; an actuator chassis connected to the pressure balance chassis, forming the upper end of the cylinder portion; a motor-electronics chassis connected to the upper end of the actuator chassis; a rod seal, providing a fluid seal between the pressure balance rod and the actuator chassis; the bladder being exposed to drilling fluid external to the MWD Tool; wherein drilling fluid pressure acting on the bladder is transferred to a fluid pressure acting on the piston; and, wherein upon disconnection of the motor-electronics chassis from the actuator chassis, the fluid in the compensating reservoir remains sealed. 2. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 1, further comprising: a valve tip connected to the lower end of the pressure balance rod; and, the cross-sectional area of the cylinder bore portion of the pressure balance chassis being substantially equal to the sum of the cross-sectional area of the valve tip plus the cross-sectional area of the pressure balance rod. 3. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 1, further comprising: the motor-electronics chassis connected to the upper end of the actuator chassis; a motor located inside the motor-electronics chassis; a gear train attached to the motor and extending into the actuator chassis; and, wherein the gear train and motor are not exposed to the pressure compensating fluid. 4. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 1, further comprising: a hollow pressure barrel removably connectable over the pressure balance chassis and the actuator chassis; and the barrel having a plurality of venting perforations positioned in alignment with the bladder such that the bladder is exposed to drilling fluid external to the MWD Tool. 5. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 1, further comprising: the actuator chassis having a pair of diametrically opposing longitudinal slits, extending to the upper end of the actuator chassis; a pair of threaded fastener holes intersecting each slit in perpendicular relation; a threaded fastener located in each fastener hole; a portal located internally of the fastener holes; a cylindrical gear train housing for a motor; the gear train housing being locatable in the portal; and, wherein tightening the fasteners in the fastener holes compresses the portal interior onto the gear train housing to secure the gear train housing in position. 6. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 5, further comprising: the gear train housing being made of a case-hardened material. 7. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 5, further comprising: the gear train housing having an outer diameter equal to or greater than the outer diameter of a motor to which it is attached. 8. An isolated pressure compensation system for a Measurement-While-Drilling Tool of claim 1, further comprising: the motor-electronics chassis connected to the upper end of the actuator chassis; a cylindrical gear train housing for a motor; a motor attached to the gear train housing; a rear plate attached to the motor; electrical connectors attached to the motor extending through the rear plate; and, the motor locatable inside the motor-electronics chassis. 9. An actuator assembly for a Measurement-While-Drilling Tool, comprising: a generally tubular actuator chassis; a pair of diametrically opposing longitudinal slits, extending along the upper end of the actuator chassis; a pair of threaded fastener holes intersecting each slit in perpendicular relation; a threaded fastener located in each fastener hole; a portal located internally of the fastener hole, the portal receivable of a cylindrical gear train housing for a motor; a rotary motor attached to the gear train housing; the gear train housing having an output shaft extending into the actuator chassis; a thrust absorbing coupling attached on a first side to the output shaft; a screw attached at one end to a second side of the coupling; a ball screw connector slidably located inside the housing and attached to the opposite end of the screw; a pin extending from the exterior of the ball screw connector, the pin located in the slot on the actuator chassis to prevent rotation of the ball screw relative to the housing; a pressure balance rod attached to the ball screw connector, the pressure balance rod extending through an opening in the bottom end of the housing; and, wherein rotation of the rotary motor causes linear movement of the pressure balance rod relative to the actuator chassis. 10. A modular Measurement-While-Drilling Tool, comprising: a lower pulser assembly receivable in a landing sub, the lower pulser having an orifice located at its upper end; a screen housing connectable to an upper end of the lower pulser assembly, and having a plurality of passages through which drilling fluid enters the MWD Tool; a pressure balance chassis removably connectable to an upper end of the screen housing; an actuator chassis removably connectable to an upper end of the pressure balance chassis; a motor-electronics chassis removably connectable to the upper end of the actuator chassis; a hollow pressure barrel connectable over the motor-electronics chassis, actuator chassis, and pressure balance chassis, and removably connectable to the upper end of the screen housing; a fluid-filled pressure compensating reservoir in axially sealed relationship within the pressure balance chassis; a pliable bladder circumferentially surrounding the pressure compensating reservoir; a pressure balance rod extending through the pressure balance chassis in slidable relation; a piston formed on the pressure balance rod, the piston being axially slidable within a cylinder bore portion of the pressure balance chassis; the compensating reservoir being in fluid communication with the cylinder bore above the piston; a valve tip on a lower end of the pressure balance rod positioned for flow restricting alignment with the orifice of the lower pulser; the pressure barrel having a plurality of venting perforations positioned in alignment with the bladder such that the bladder is exposed to drilling fluid external to the MWD Tool; wherein drilling fluid pressure acting on the valve tip is substantially compensated by fluid pressure in the compensating reservoir acting on the piston; and, wherein upon disconnection of the motor-electronics chassis from the actuator chassis, the fluid in the compensating reservoir remains axially sealed within the pressure balance assembly.